1. Field of the Invention
The present invention relates to car navigation, and more particularly, to a method, apparatus, and medium for three-dimensionally transforming two-dimensional flyover data in a three-dimensional graphics environment and a method, apparatus, and medium for three-dimensionally visualizing two-dimensional flyover data in a three-dimensional graphics environment.
2. Description of the Related Art
Recently, an increase in the number of cars on roads has caused a serious problem of traffic congestion. In order to solve the traffic congestion, there have been developed car navigation systems such as a global positioning system (GPS). The car navigation system has basic functions of tracking a position of a car and displaying the position on a road map. The car navigation system has additional functions of monitoring traffic situations on roads and providing traffic situation information to drivers.
A well-visualized car navigation system enables drivers to accurately locate their destination on the road map. In addition, when a car runs at a high speed, a three-dimensionally visualized road map of the car navigation system provides more convenience and safety to a driver than a two-dimensional map does. Buildings and geographical features are depicted three-dimensionally on the three-dimensionally visualized road map, so that drivers can perceive them intuitively.
Conventional car navigation systems store two-dimensional data and visualize the data two-dimensionally. Since complex objects such as flyovers are two-dimensionally visualized, the users may confuse the objects.
FIGS. 1A and 1B are views showing three-dimensionally visualized flyover data according to a conventional method. Referring to FIG. 1A, two different parts of a flyover having different heights are overlapped at a portion indicated by 1. If a flyover is two-dimensionally visualized, the other parts of a flyover seem to intersect each other on the same plane. Therefore, inaccurate road information may be provided to users. In addition, as shown in FIG. 1B, flyover data may be displayed according to an order of arrangement of vertexes of a polygon constituting the flyover data.
In a three-dimensional graphics environment, in a case where different parts of an object do not exist on the same plane (a non-coplanar case) or a case where projections of the different parts of an object on the same plane intersect each other (a self-intersection case), visualization of an object may not be accurate. Since the flyover data belongs to the two cases, it is necessary to transform the two-dimensional flyover data to three-dimensional flyover data with a particular process.